package com.bobo.MD5;

import java.security.*;
/**
 * Java 实现消息摘要 (可通过 hexDigits[byte0 >>> 3 & 0xf] 改变位移参数,实现不同MD5值)
 * @author win7
 *  MD5值是不可逆转的 (目前无法破解,可用于加密用户密码 存储在数据库)
 */
public class MD5_test {

	public final static String MD5(String s) {
		char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
		try {
			byte[] strTemp = s.getBytes();
			MessageDigest mdTemp = MessageDigest.getInstance("MD5");
			mdTemp.update(strTemp);
			byte[] md = mdTemp.digest();
			int j = md.length;
			char str[] = new char[j * 2];
			int k = 0;
			for (int i = 0; i < j; i++) {
				byte byte0 = md[i];
				str[k++] = hexDigits[byte0 >>> 3 & 0xf];
				str[k++] = hexDigits[byte0 >>> 1 & 0xf];
			}
			return new String(str);
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	public static void main(String[] args) {
		System.out.print(MD5_test.MD5("bobo"));
	}
}
